Electric drives are used in industry for different applications, such as for driving motors within the transportation industry, for driving different devices within the process and manufacturing industry as well as within the energy industry. There are applications commonly used for electric drives within the transportation industry for example in metro and railway traffic applications as well as in ship propulsion unit applications of the marine industry. Within the process and manufacturing industry, electric drives can be used for example in conveyor applications, in mixer applications or even in paper machine applications. Within the energy industry, electric drives can be used for example as electric drives for wind turbines of the wind power industry and as electric drives of the solar power industry.
Electric drives for electric motors may be divided into DC motor drives (DC, direct current) and AC drives (AC, alternating current). In a DC motor of a DC motor drive, a magnetic field is generated by the current through the field winding in the stator. This magnetic field is always maintained at right angles to the field generated by the armature winding. In this way, a DC motor's torque is generated, which torque can then be easily controlled in a DC motor drive by changing the armature current and keeping the magnetizing current constant. In a DC motor drive, also the DC motor speed can be controlled directly through armature current.
Within electric drives, the AC drives may further be divided into frequency-controlled AC drives, flux-vector-controlled AC drives and into AC drives utilising direct torque control (DTC, Direct Torque Control). In flux-vector-controlled AC drives and in direct torque control AC drives the torque of the three-phase motor can be controlled, whereas in frequency controlled AC drives the load dictates the torque level.
The evolvement of communication technology, particularly wireless communication technology and end user devices, has enabled versatile communication possibilities and introduction of different services. An example of such a service is a remote support for maintenance staff of machines and equipment such as electric drive apparatuses. There are smartphone applications that allow a user of the smartphone to receive service recommendations for a machine, store operational data on the machine over the network connection, and troubleshoot the machine, for example, from a service center.